Acronym for Kraft Dinner, the Canadian version of Kraft Macaroni and Cheese. It's called KD in Canada, because Canadians consider this to be an entire dinner. Whereas in America, we consider it a side dish.

Canadian child: "Mom, how aboot you put down the bottle and make me some KD? I want to play hockey before the ice melts."

The act of just writing k in a text/im. People generally don't like responding to such a small answer thus being k'd generally ends the conversation. If you are the one being k'd, you should assume the person that k'd you is either very mad at you, or very pissy.

1: Hey, are you ok? You seem upset.
2: I don't wanna talk about it.
1: Well I'm here if you do
2: k.
1: *thinks to them self* Wow, I can't believe he just k'd me! I'm not answering that!